Cages, especially large cages for large birds, rabbits or a large number of smaller animals take up a relatively large amount of space in storage and during transport. In order to save on storage space or to obtain smaller shipping units, it has already been proposed that cages should be designed as collapsible structures, so that in the collapsed state they take up only a fraction, for example only one quarter to one fifth, of the space required by the fully assembled cage.
The purchaser of a cage normally acquires the cage in the collapsed state so that he, too, has only a small unit to transport. On the other hand, however, he has to assemble the cage once he gets it home. It must be possible to do this without the need for any special technical skills or tools. For this reason, it has been suggested that, for example in the case of a box-shaped cage having four lateral corners, each corner should be formed by a sectional corner connector into which adjacent lateral edges, which are vertical when in use, or outer edge zones of the wire gratings, are longitudinally inserted. The sectional corner connector is provided with a groove for each of the two lateral edge zones of the wire gratings. However, these grooves must be designed and adapted to the lateral edge zones of the wire gratings in such a way that these latter cannot be pulled out of the grooves in the horizontal direction. It must be remembered here that the lateral edge zone of the wire gratings may consist of at least one vertical grating bar and a plurality of horizontal grating bars welded to it. In the known type of collapsible cage, it is precisely this design of the two edge zones that makes it very difficult, and requires the application of force, to insert the two walls into the sectional corner connectors. It would be possible to make the grooves, wider, but this would have the disadvantage that the cage would then lose its stability. This method of assembly is inherently unsuitable for the layman.